1 files changed, 2 insertions, 1 deletions

diff --git a/src/Network/Tox/NodeId.hs b/src/Network/Tox/NodeId.hs
index d5da692a..dc600db7 100644
--- a/src/Network/Tox/NodeId.hs
+++ b/src/Network/Tox/NodeId.hs
@@ -589,7 +589,8 @@ parseNoSpamJID jid = do
 
 solveBase64NoSpamID :: String -> PublicKey -> Either String NoSpamId
 solveBase64NoSpamID b64digits pub = do
-    NoSpam nospam (Just x) <- readEither $ '$' : map (\case; '?' -> '0'; c -> c) b64digits
+    NoSpam nospam mx <- readEither $ '$' : map (\case; '?' -> '0'; c -> c) b64digits
+    maybe (const $ Left "missing checksum") (flip ($)) mx $ \x -> do
     let nlo = fromIntegral (0x0FFFF .&. nospam) :: Word16
         nhi = fromIntegral (0x0FFFF .&. (nospam `shiftR` 16)) :: Word16
         sum = x `xor` nlo `xor` nhi `xor` xorsum pub